Winding structure and battery

Abstract

Provided in the present application are a winding structure and a battery. The winding structure comprises a positive electrode sheet, a negative electrode sheet, and a first separator and a second separator which are arranged between the positive electrode sheet and the negative electrode sheet; the centerline of the winding structure in the width direction is the midline of the winding structure, the position where the positive electrode sheet is bent for the first time is a first bending area, the area where the negative electrode sheet is bent for the first time is a second bending area, and the first bending area and the second bending area are located on the two sides of the midline; and a second inner paste coating layer located in the first bending area is a deactivated layer, and the deactivated layer has a lower content of deintercalatable lithium than other second inner paste coating layers. In this way, during the charging of a battery comprising the winding structure, the amount of lithium ions deintercalated from the deactivated layer to an end of the negative electrode sheet located at the winding center of the winding structure is reduced, thereby slowing down lithium plating at the end of the negative electrode sheet, thus reducing the possibility of a short circuit in the battery due to lithium plating, and improving the safety of the battery during use.

Description

Winding structure and battery Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a winding structure and a battery.

[0002] Background of the Invention

[0003] In a wound lithium-ion battery, the head end face of the negative electrode sheet at the center of the winding structure is far away from the coating of the opposite positive electrode sheet (to prevent the head end face of the negative electrode sheet from touching the positive electrode sheet and bending, a farther space is reserved). Since there is less active material on the head end face of the negative electrode sheet, when the battery is charging, the lithium ions of the positive electrode sheet coating facing the head end face of the negative electrode are not absorbed by enough negative electrode active material, resulting in lithium deposition short circuit in the battery, which seriously affects the safety of the battery.

[0004] Summary of the Invention

[0005] In view of this, the present application provides a winding structure that solves the problem of lithium deposition short circuit in the battery. The present application also provides a battery including the winding structure.

[0006] The present application provides a wound structure, comprising a positive electrode sheet, a negative electrode sheet, and a first separator and a second separator disposed between the positive electrode sheet and the negative electrode sheet, the negative electrode sheet comprising a negative current collector and a first inner paste layer and a first outer paste layer disposed on opposite surfaces of the negative current collector, the positive electrode sheet comprising a positive current collector and a second inner paste layer and a second outer paste layer disposed on opposite surfaces of the positive current collector, the second inner paste layer being disposed on a surface close to a winding center of the wound structure, and the second outer paste layer being disposed on a surface facing away from the winding center, the centerline of the wound structure in the width direction being the midline of the wound structure, the location where the positive electrode sheet first bends being the first bending zone, the region where the negative electrode sheet first bends being the second bending zone, the first bending zone and the second bending zone being located on either side of the midline, the second inner paste layer located in the first bending zone being a deactivation layer, and the deactivation layer having a lower content of deintercalable lithium than the remaining second inner paste layers.

[0007] Optionally, the deactivation layer is a laser scanning layer or a physical etching layer.

[0008] Optionally, the resistance of the deactivation layer is R1, and the resistance of the second inner paste layer is R2, wherein R1 and R2 satisfy: R1≥1.2*R2.

[0009] Optionally, the compaction density of the deactivated layer is ρ1, and the compaction density of the second inner pasting layer is ρ2, wherein ρ1 and ρ2 satisfy: ρ1≤0.85*ρ2.

[0010] Optionally, the deactivation layer further includes barrier particles, and the barrier particles are located on a surface of the deactivation layer close to an end of the negative electrode sheet.

[0011] Optionally, the barrier particles include spinel-structured lithium cobalt oxide.

[0012] Optionally, in the width direction of the positive electrode sheet, the size of the deactivation layer is equal to the size of the positive electrode sheet.

[0013] Optionally, in the length direction of the positive electrode sheet, the size of the deactivation layer is 2 mm-20 mm.

[0014] Optionally, in a direction perpendicular to the straight section of the negative electrode sheet located at the winding center of the winding structure, the deactivation layer and the straight section of the negative electrode sheet overlap, and a dimension of the overlapping area in the width direction of the winding structure is 2 mm-20 mm.

[0015] Optionally, it also includes an insulating layer arranged on the surface of the deactivation layer close to the winding center of the winding structure, and in the direction perpendicular to the positive electrode sheet, the sum of the sizes of the insulating layer and the deactivation layer is less than or equal to the size of the second inner paste layer.

[0016] Optionally, in the length direction of the positive electrode sheet, the size of the insulating layer is 2 mm to 15 mm, and the size of the insulating layer is smaller than the size of the deactivation layer, and the distance from the insulating layer to the second inner paste layer is 0.5 mm to 5 mm.

[0017] Optionally, in the length and / or width direction of the positive electrode sheet, the size of the insulating layer is larger than the size of the deactivation layer.

[0018] Optionally, in the width direction of the positive electrode sheet, the size of the insulating layer is larger than the size of the positive electrode sheet.

[0019] Optionally, the total number of layers of the first separator and the second separator between the straight section of the negative electrode sheet and the straight section of the positive electrode sheet at the winding center of the winding structure is S, where S satisfies: 1≤S≤3.

[0020] Optionally, the minimum distance between the end of the negative electrode sheet at the winding center of the winding structure and the end of the first diaphragm and the distance between the end of the negative electrode sheet at the winding center of the winding structure and the end of the second diaphragm is L1, and the dimension of the straight section of the negative electrode sheet located at the winding center of the winding structure in the width direction of the winding structure is L2, where L1 and L2 satisfy: 5mm≤L1≤L2.

[0021] Optionally, the remaining bending position of the positive electrode sheet is a third bending zone, and at least a part of the second inner paste layer located in the third bending zone is an inactivated layer.

[0022] Optionally, at least a portion of the second inner paste layer located in the third bending region is provided with an insulating layer.

[0023] The present application also provides a battery comprising any one of the winding structures described above.

[0024] The winding structure provided in the present application is characterized by setting the second inner paste layer located in the first bending area as a deactivation layer, and the content of removable lithium in the deactivation layer is lower than the content of removable lithium in the remaining second inner paste layers. In this way, during the charging process of the battery composed of the winding structure, the amount of lithium ions released from the deactivation layer to the end of the negative electrode sheet located at the winding center of the winding structure is reduced, thereby slowing down the lithium deposition at the end of the negative electrode sheet, thereby reducing the possibility of short circuit of the battery due to lithium deposition, and improving the safety of the battery during use.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0027] FIG1 is a front view of a winding structure provided in one embodiment of the present application.

[0028] FIG2 is a partial enlarged view of FIG1 .

[0029] FIG3 is a front view of a winding structure provided in another embodiment of the present application.

[0030] FIG4 is a partial enlarged view of FIG2 .

[0031] FIG5 is a side view of a positive electrode sheet in an unfolded state provided in one embodiment of the present application.

[0032] FIG6 is a side view of a positive electrode sheet in an unfolded state provided by another embodiment of the present application.

[0033] FIG7 is a partial enlarged view of a winding core structure provided by another embodiment.

[0034] FIG8 is a side view of a positive electrode sheet in an unfolded state provided by another embodiment.

[0035] FIG9 is a side view of a negative electrode sheet in an unfolded state provided in one embodiment of the present application.

[0036] FIG10 is a schematic diagram of the positive electrode sheet and the negative electrode sheet in an unfolded state after the wound structure is assembled into a battery and charged, provided by an embodiment of the present application.

[0037] FIG11 is an XRD pattern of the second inner pasting layer.

[0038] FIG12 is an XRD pattern of the deactivated layer.

[0039] FIG13 is a SEM image of the inactivated region.

[0040] In Figures 1-13:

[0041] 1-negative electrode sheet, 2-positive electrode sheet, 3-first separator, 4-second separator, 5-insulating layer;

[0042] 11-negative current collector, 12-first inner paste layer, 13-first outer paste layer, 14-straight section of negative electrode sheet, 15-end of negative electrode sheet, 16-second bending zone, 21-positive current collector, 22-second inner paste layer, 23-second outer paste layer, 24-first bending zone, 25-deactivation layer, 26-straight section of positive electrode sheet, 27-third bending zone.

[0043] Modes for Carrying Out the Invention

[0044] The present application provides a winding structure and a battery comprising the winding structure.

[0045] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0046] As shown in Figures 1 to 13, an embodiment of the present application provides a winding structure that can be used together with a shell and other components to form a battery. The winding structure mainly includes a positive electrode sheet 2, a negative electrode sheet 1, and a first separator 3 and a second separator 4 arranged between the positive electrode sheet 2 and the negative electrode sheet 1. The negative electrode sheet 1 includes a negative current collector 11 and a first inner paste layer 12 and a first outer paste layer 13 arranged on two opposite surfaces of the negative current collector 11. The positive electrode sheet 2 includes a positive current collector 21 and a second inner paste layer 22 and a second outer paste layer 23 arranged on two opposite surfaces of the positive current collector 21. The second inner paste layer 22 is arranged on the surface close to the winding center of the winding structure, and the second outer paste layer 23 is arranged on the surface away from the winding center. Among them, the center line of the winding structure in the width direction is the center line of the winding structure, the position where the positive electrode sheet 2 first bends is the first bending zone 24, and the area where the negative electrode sheet 1 first bends is the second bending zone 16. The first bending zone 24 and the second bending zone 16 are located on both sides of the center line.

[0047] In this embodiment, the second inner pasted layer 22 located in the first bend region 24 serves as a deactivation layer 25, and the deactivation layer 25 has a lower deintercalable lithium content than the remaining second inner pasted layers 22. It should be noted that the lower deintercalable lithium content in the deactivation layer 25 than in the remaining second inner pasted layers 22 ensures that, after the wound structure is assembled into a battery, at least some of the lithium ions in the deactivation layer 25 are prevented from being released from the deactivation layer 25 and transferred to the negative electrode sheet 1 during charging. During charging and discharging, the amount of lithium ions released from the deactivation layer 25 decreases, and the end 15 of the negative electrode sheet near the deactivation layer 25 absorbs less lithium ions. This results in a reduced amount of lithium ions released from the end 15 of the negative electrode sheet 1 located at the center of the wound structure, or even no lithium ions being released, thereby preventing the battery from short-circuiting due to lithium deposition.

[0048] It should be noted that the remaining second inner pasting layers 22 refer to the second inner pasting layers 22 located in other areas outside the first bending area 24 .

[0049] It should also be noted that the winding center of the winding structure refers to the area where the center of the winding structure is located.

[0050] The winding structure of the above structure is configured such that the second inner pasted layer 22 located in the first bending region 24 is provided as a deactivation layer 25, and the content of deintercalable lithium in the deactivation layer 25 is lower than the content of deintercalable lithium in the remaining second inner pasted layers 22. Thus, during the charging process of the battery composed of the winding structure, the amount of lithium ions released from the deactivation layer 25 toward the end 15 of the negative electrode sheet located at the winding center of the winding structure is reduced, thereby slowing down the lithium deposition at the end of the negative electrode sheet 1, thereby reducing the possibility of short circuit of the battery due to lithium deposition, and improving the safety of the battery during use.

[0051] In some embodiments, the inactivation layer 25 is a laser scanning layer or a physical etching layer.

[0052] It should be noted that the laser scanning layer refers to a layered structure formed by laser scanning the second inner paste layer 22, and the physical etching layer refers to a layered structure formed by physical etching the second inner paste layer 22. Laser scanning, physical etching, or other methods are used to treat the second inner paste layer 22, so that the conductive agent in the coating in that area changes, the compaction density of the coating decreases, the inter-particle structure of the coating material changes, or the lithium cobalt oxide undergoes a phase change to form spinel lithium cobalt oxide with reduced lithium insertion and removal capabilities. This reduces the conductivity of that area, reduces the amount of lithium that can be inserted and removed, or even eliminates it, thereby preventing lithium deposition in the corresponding negative electrode area.

[0053] In some embodiments, the resistance of the deactivation layer 25 is R1, and the resistance of the second inner paste layer 22 is R2, where R1 and R2 satisfy the following relationship: R1 ≥ 1.2 * R2; and / or the compaction density of the deactivation layer 25 is ρ1, and the compaction density of the second inner paste layer 22 is ρ2, where ρ1 and ρ2 satisfy the following relationship: ρ1 ≤ 0.85 * ρ2. Specifically, by setting the resistance and compaction density of the deactivation layer 25 relative to the resistance and compaction density of the second inner paste layer 22 within the aforementioned ranges, the deactivation layer 25 can have a lower deintercalable lithium content than the second inner paste layer 22, thereby mitigating lithium deposition at the end 15 of the negative electrode sheet at the center of the wound structure, thereby improving battery safety.

[0054] It should be noted that the present application is not limited to processing the second inner paste layer 22 by laser scanning and physical etching methods so that the resistance and compaction density of the deactivated layer 25 obtained after processing the second inner paste layer 22 satisfy the above relationship with those of the untreated second inner paste layer 22. Using other methods to process the second inner paste layer 22 so that the resistance and compaction density of the deactivated layer 25 obtained after processing the second inner paste layer 22 satisfy the above relationship with those of the untreated second inner paste layer 22 is also within the scope of protection of this solution.

[0055] Exemplarily, the resistance R1 of the deactivation layer 25 can be 1.2R2, 1.3R2, 1.4R2, 1.5R2, 1.8R2, 2R2, 3R2, 5R2, etc., where R2 is the resistance of the second inner paste layer 22; the compaction density of the deactivation layer 25 can be 0.85ρ2, 0.82ρ2, 0.8ρ2, 0.75ρ2, 0.7ρ2, 0.6ρ2, 0.5ρ2, etc., where ρ2 is the compaction density of the second inner paste layer 22.

[0056] Furthermore, in some embodiments, the deactivation layer 25 further includes barrier particles, and the barrier particles are located on the surface of the deactivation layer 25 near the end of the negative electrode sheet 1. Specifically, the second inner paste layer 22 is laser scanned or physically etched to form the deactivation layer 25, and fine particles are attached to the surface of the deactivation layer 25. During the charging process of the battery having the above-mentioned wound structure, the fine particles have a weak ability to deintercalate and release lithium. This further reduces the amount of lithium ions released from the first bend region 24, further alleviating lithium deposition at the end of the negative electrode sheet 1 corresponding to the first bend.

[0057] In some embodiments, the barrier particles include spinel-structured lithium cobalt oxide. Specifically, the spinel-structured lithium cobalt oxide primarily refers to spinel lithium cobalt oxide. This spinel lithium cobalt oxide is caused by the high temperature of the laser and is a side effect. However, spinel lithium cobalt oxide's ability to deintercalate lithium is inferior to that of conventional layered lithium cobalt oxide. Therefore, although this is a side effect, it can further mitigate the problem of lithium ions migrating from the first bend region 24 to the end 15 of the negative electrode sheet, thereby improving lithium deposition at the end of the negative electrode sheet 1 corresponding to the first bend region 24.

[0058] In some embodiments, the spinel structure lithium cobalt oxide content accounts for 5% to 80% of the total lithium cobalt oxide content of the deactivation layer 25. Specifically, because the spinel structure lithium cobalt oxide has a lower lithium insertion and removal ability than conventional layered lithium cobalt oxide, the greater the proportion of the spinel structure lithium cobalt oxide content in the deactivation layer 25, the weaker the ability of the deactivation layer 25 to lose lithium ions during charging of the battery having the above-mentioned wound structure, and the stronger the effect of improving lithium deposition at the end of the negative electrode sheet 1 corresponding to the first bend region 24.

[0059] For example, the content of the spinel structure lithium cobalt oxide in the total lithium cobalt oxide content of the deactivation layer 25 may be 5%, 10%, 20%, 40%, 50%, 60%, 80%, etc.

[0060] In some embodiments, the size of the deactivation layer 25 is equal to the size of the positive electrode sheet 2 in the width direction of the positive electrode sheet 2; and / or, the size of the deactivation layer 25 is 2mm-20mm in the length direction of the positive electrode sheet 2. Specifically, in the width direction of the positive electrode sheet 2, the size of the deactivation layer 25 is equal to the size of the positive electrode sheet 2. That is, by laser scanning and physical etching, the entire second inner paste layer 22 in the first bending area 24 of the positive electrode sheet 2 near the end of the negative electrode sheet 1 is processed. This can reduce the content of deintercalable lithium in the coating near the end of the negative electrode sheet 1 in the first bending area 24, thereby slowly releasing lithium. In the length direction of the positive electrode sheet 2, the size of the deactivation layer 25 is 2mm-20mm, ensuring that the coating at the end 15 of the negative electrode sheet near the winding center of the winding structure in the first bending area 24 is all the deactivation layer 25, and the size of the deactivation layer 25 is flexibly set according to the winding structure of different specifications.

[0061] It should be noted that the length direction of the positive electrode sheet 2 refers to the direction indicated by the double-headed arrow A in FIG5 , and the width direction of the positive electrode sheet 2 refers to the direction indicated by the double-headed arrow E in FIG5 , and the direction indicated by the double-headed arrow E is perpendicular to the direction indicated by the double-headed arrow A.

[0062] In some embodiments, in the direction of the straight section 14 of the negative electrode sheet located perpendicular to the winding center of the winding structure, the projection of the deactivation layer 25 overlaps with the straight section 14 of the negative electrode sheet, and the size of the overlapping area in the width direction of the winding structure is 2mm-20mm. Specifically, it is ensured that in the direction of the straight section 14 of the negative electrode sheet located perpendicular to the winding center of the winding structure, the projection of the deactivation layer 25 overlaps with the straight section 14 of the negative electrode sheet, that is, the coating at the end of the negative electrode sheet 1 in the first bending area 24 near the winding center of the winding structure is all the deactivation layer 25, which can further ensure the size of the deactivation layer 25 and alleviate or avoid lithium deposition at the end 15 of the negative electrode sheet. Ensuring that the size of the overlapping area in the width direction of the winding structure is 2mm-20mm can ensure that the size of the deactivation layer 25 exceeds the size of the straight section 14 of the negative electrode sheet, further alleviating or avoiding lithium deposition at the end 15 of the negative electrode sheet.

[0063] It should be noted that the direction of the straight section 14 of the negative electrode sheet perpendicular to the winding center of the winding structure refers to the direction indicated by the double-headed arrow B in FIG1 , and the width direction of the winding structure refers to the direction indicated by the double-headed arrow C in FIG1 .

[0064] It should also be noted that the straight section 14 of the negative electrode sheet at the winding center of the winding structure refers to the unbent straight portion of the negative electrode sheet 1 located at the winding center of the winding structure.

[0065] Furthermore, in some embodiments, the wound structure further includes an insulating layer 5 disposed on a surface of the deactivation layer 25 near the winding center of the wound structure, and in a direction perpendicular to the positive electrode sheet 2, the sum of the dimensions of the insulating layer 5 and the deactivation layer 25 is less than or equal to the dimension of the second inner paste layer 22. Specifically, the insulating layer 5 is disposed on a surface of the deactivation layer 25 near the winding center of the wound structure, and is attached to the deactivation layer 25. The insulating layer 5 can isolate lithium ions in the first bending region 24 from migrating toward the end 15 of the negative electrode sheet during battery charging. While the deactivation layer 25 alleviates or prevents lithium deposition at the end 15 of the negative electrode sheet, the provision of the insulating layer 5 can further prevent lithium deposition at the end 15 of the negative electrode sheet, thereby achieving a dual protection effect of preventing lithium deposition at the end of the negative electrode sheet 1. In the direction perpendicular to the positive electrode sheet 2, it is further ensured that the sum of the sizes of the insulating layer 5 and the deactivation layer 25 is less than or equal to the size of the second inner paste layer 22. This can avoid the increase in the size of the winding structure due to the provision of the insulating layer 5, thereby avoiding the winding structure from generating an invalid thickness, thereby avoiding reducing the energy density of the battery composed of the winding structure.

[0066] It should be noted that the direction perpendicular to the positive electrode sheet 2 refers to the direction indicated by the double-headed arrow D in FIG. 5 .

[0067] It should be noted that the insulating layer 5 may be an insulating structure such as insulating tape.

[0068] In some embodiments, the size of the insulating layer 5 is ensured to be 2 mm to 15 mm in the longitudinal direction of the positive electrode sheet 2, and the size of the insulating layer 5 is smaller than the size of the deactivation layer 25. In this manner, the insulating layer 5 does not overlap the second inner paste layer 22 next to the deactivation layer 25, thereby further ensuring that the size of the wound structure is not increased, thereby avoiding affecting the energy density of the battery composed of the wound structure. Furthermore, the distance from the insulating layer 5 to the second inner paste layer 22 is ensured to be 0.5 mm to 5 mm. A gap of 0.5 mm to 5 mm is left between the insulating layer 5 and the second inner paste layer 22, which improves the production yield and efficiency. The gap can also store electrolyte, increase the battery's liquid retention, and extend the cycle life of the lithium-ion battery. In the width direction of the positive electrode sheet 2, the size of the insulating layer 5 is larger than the size of the positive electrode sheet 2. Such a configuration can achieve full coverage of the deactivation layer 25 by the insulating layer 5 in the width direction of the positive electrode sheet 2, thereby preventing the deactivation layer 25 from being exposed to the outside in the width direction of the positive electrode sheet 2, thereby further preventing lithium ions from moving from the deactivation layer 25 to the negative electrode sheet 1 during charging, and preventing lithium deposition on the negative electrode sheet 1.

[0069] It should be noted that the length direction of the positive electrode sheet 2 refers to the direction indicated by the double-headed arrow A in FIG5 , and the width direction of the positive electrode sheet 2 refers to the direction indicated by the double-headed arrow E in FIG5 , and the direction indicated by the double-headed arrow E is perpendicular to the direction indicated by the double-headed arrow A.

[0070] In other embodiments, as shown in Figures 7 and 8, the dimensions of the insulating layer 5 are larger than the dimensions of the deactivated layer 25 in the length and / or width directions of the positive electrode sheet 2. Because the deactivated layer is located in the first bend region of the positive electrode sheet and is subject to certain stress, and because the surface of the deactivated layer is composed of rough, granular dust, there is a risk that the insulating layer may fall off when attached to the deactivated layer. Therefore, when the dimensions of the insulating layer 5 are larger than the dimensions of the deactivated layer 25, the insulating layer can be attached to the second inner paste layer connected to both sides of the deactivated layer, ensuring that the insulating layer covers the deactivated layer, reducing lithium ion escape from this region, and making the insulating layer 5 more firmly attached.

[0071] In some embodiments, the total number of layers of the first separator 3 and the second separator 4 between the straight section 14 of the negative electrode sheet and the straight section 26 of the positive electrode sheet located at the winding center of the winding structure is S, where S satisfies: 1≤S≤3. Specifically, when the total number of separator layers between the straight section 14 of the negative electrode sheet and the straight section 26 of the positive electrode sheet is 1, the separator can be either the first separator 3 or the second separator 4. When the total number of separator layers between the straight section 14 of the negative electrode sheet and the straight section 26 of the positive electrode sheet is 2, the separator can be two first separators 3, or two second separators 4, or one first separator 3 and one second separator 4. When the total number of separator layers between the straight section 14 of the negative electrode sheet and the straight section 26 of the positive electrode sheet is 3, the separator is preferably one first separator 3 and two second separators 4, or one second separator 4 and two first separators 3. Ensure that the total number of diaphragm layers between the straight section 14 of the negative electrode sheet and the straight section 26 of the positive electrode sheet meets the above range, avoid "Z"-shaped or "U"-shaped overlap of the starting sections of the first diaphragm 3 and the second diaphragm 4 at the beginning of the winding structure, avoid thickening of the winding structure, and avoid reduction of battery energy density.

[0072] It should be noted that the straight section 14 of the negative electrode sheet at the winding center of the winding structure refers to the unbent straight portion of the negative electrode sheet 1 located at the winding center of the winding structure, and the straight section 26 of the positive electrode sheet at the winding center of the winding structure refers to the unbent straight portion of the positive electrode sheet 2 located at the winding center of the winding structure.

[0073] In some embodiments, the minimum distance between the end 15 of the negative electrode sheet at the center of the winding structure and the end of the first separator 3, and the minimum distance between the end 15 of the negative electrode sheet at the center of the winding structure and the end of the second separator 4 is L1, and the dimension of the straight section 14 of the negative electrode sheet located at the center of the winding structure in the width direction of the winding structure is L2, where L1 and L2 satisfy the following: 5mm≤L1≤L2. Ensuring 5mm≤L1 is to prevent the separator from leaking out of the end 15 of the negative electrode sheet at the center of the winding structure when the winding structure falls or is vibrated, causing the separator to shrink, thereby preventing safety issues caused by short circuits between the positive and negative electrodes; ensuring L1≤L2 is to avoid excessive separator distance, which will cause the winding structure to thicken and avoid affecting the energy density of the battery.

[0074] It should be noted that the minimum distance between the distance between the end 15 of the negative electrode sheet at the winding center of the winding structure and the end of the first separator 3 and the distance between the end 15 of the negative electrode sheet at the winding center of the winding structure and the end of the second separator 4 refers to the dimension of the shorter distance from the end 15 of the negative electrode sheet to the end of the first separator 3 and the end of the second separator 4.

[0075] In some embodiments, the remaining bends in the positive electrode sheet are located at a third bend region 27. At least a portion of the second inner paste layer 22 located in the third bend region 27 is an inactivated layer, and / or at least a portion of the second inner paste layer 22 located in the third bend region 27 is provided with an insulating layer. Specifically, the area of ​​the second inner paste layer 22 on the side of the third bend region 27 near the winding center of the wound structure is larger than the area of ​​the adjacent first outer paste layer 13. Consequently, during battery charging, the second inner paste layer 22 located in the third bend region 27 releases more lithium ions, while the first outer paste layer 13 near the third bend region 27 has fewer lithium ion adsorption sites, resulting in lithium deposition on the surface of the first outer paste layer 13. Here, by making at least a portion of the coating on the side of the third bending zone 27 close to the winding center of the winding structure a deactivation layer 25, and / or, at least a portion of the coating on the side of the third bending zone 27 close to the winding center of the winding structure is provided with an insulating layer 5, such a setting can reduce the content of deintercalable lithium in the coating on the side of the third bending zone 27 close to the winding center of the winding structure, or block the release of lithium ions in the coating on the side of the third bending zone 27 close to the winding center of the winding structure, thereby alleviating lithium deposition on the surface of the first outer coating layer 13, or even avoiding lithium deposition on the surface of the first outer coating layer 13.

[0076] A battery comprising any of the above-mentioned winding structures. The beneficial effects of the winding structure on the battery are described above and will not be elaborated on here.

[0077] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0078] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0079] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0080] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0081] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly illustrate the technical solutions and cannot be used to limit the scope of protection of the present application.

[0082] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A winding structure, characterized in that: The invention comprises a positive electrode sheet, a negative electrode sheet, and a first separator and a second separator arranged between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet comprises a negative current collector and a first inner paste layer and a first outer paste layer arranged on two opposite surfaces of the negative current collector, and the positive electrode sheet comprises a positive current collector and a second inner paste layer and a second outer paste layer arranged on two opposite surfaces of the positive current collector, wherein the second inner paste layer is arranged on a surface close to the winding center of the winding structure, and the second outer paste layer is arranged on a surface away from the winding center. The center line of the winding structure in the width direction is the midline of the winding structure, the location where the positive electrode sheet is bent for the first time is the first bending area, the area where the negative electrode sheet is bent for the first time is the second bending area, and the first bending area and the second bending area are located on both sides of the midline; The second inner pasted layer located in the first bending area is a deactivated layer, and the deactivated layer has a lower content of deintercalable lithium than the rest of the second inner pasted layer.

2. The winding structure according to claim 1, characterized in that: The deactivation layer is a laser scanning layer or a physical etching layer.

3. The winding structure according to claim 1 or 2, characterized in that: The resistance of the deactivation layer is R1, and the resistance of the second inner paste layer is R2, wherein R1 and R2 satisfy: R1≥1.2*R2.

4. The winding structure according to any one of claims 1 to 3, characterized in that: The compaction density of the deactivation layer is ρ1, and the compaction density of the second inner paste layer is ρ2, wherein ρ1 and ρ2 satisfy: ρ1≤0.85*ρ2.

5. The winding structure according to any one of claims 1 to 4, characterized in that: The deactivation layer further includes barrier particles, and the barrier particles are located on a surface of the deactivation layer close to an end of the negative electrode sheet.

6. The winding structure according to claim 5, characterized in that: The barrier particles include spinel structure lithium cobalt oxide.

7. The winding structure according to any one of claims 1 to 6, characterized in that: In the width direction of the positive electrode sheet, the size of the deactivation layer is equal to the size of the positive electrode sheet.

8. The winding structure according to any one of claims 1 to 7, characterized in that: In the length direction of the positive electrode sheet, the size of the deactivation layer is 2 mm-20 mm.

9. The winding structure according to any one of claims 1 to 8, characterized in that: In a direction perpendicular to the straight section of the negative electrode sheet located at the winding center of the winding structure, the deactivation layer and the straight section of the negative electrode sheet overlap, and a dimension of the overlapping area in the width direction of the winding structure is 2 mm-20 mm.

10. The winding structure according to any one of claims 1 to 9, characterized in that: It also includes an insulating layer arranged on the surface of the deactivation layer on one side close to the winding center of the winding structure, and in the direction perpendicular to the positive electrode sheet, the sum of the sizes of the insulating layer and the deactivation layer is less than or equal to the size of the second inner paste layer.

11. The winding structure according to claim 10, characterized in that: In the length direction of the positive electrode sheet, the size of the insulating layer is 2 mm to 15 mm, and the size of the insulating layer is smaller than the size of the deactivation layer. The distance from the insulating layer to the second inner paste layer is 0.5 mm to 5 mm.

12. The winding structure according to claim 10, characterized in that: In the length and / or width direction of the positive electrode sheet, the size of the insulating layer is larger than the size of the deactivation layer.

13. The winding structure according to any one of claims 10 to 12, characterized in that: In the width direction of the positive electrode sheet, the size of the insulating layer is larger than the size of the positive electrode sheet.

14. The winding structure according to any one of claims 1 to 13, characterized in that: The total number of layers of the first separator and the second separator between the straight section of the negative electrode sheet and the straight section of the positive electrode sheet located at the winding center of the winding structure is S, where S satisfies: 1≤S≤3.

15. The winding structure according to any one of claims 1 to 14, characterized in that: The minimum distance between the end of the negative electrode sheet at the winding center of the winding structure and the end of the first separator and the distance between the end of the negative electrode sheet at the winding center of the winding structure and the end of the second separator is L1, and the dimension of the straight section of the negative electrode sheet located at the winding center of the winding structure in the width direction of the winding structure is L2, where L1 and L2 satisfy: 5mm≤L1≤L2.

16. The winding structure according to any one of claims 1 to 15, characterized in that: The remaining bending position of the positive electrode sheet is a third bending zone, and at least a part of the second inner paste layer located in the third bending zone is a deactivated layer.

17. The winding structure according to any one of claims 1 to 16, characterized in that: At least a portion of the second inner paste layer located in the third bending area is provided with an insulating layer.

18. A battery, characterized in that: Comprising a wound structure as claimed in any one of claims 1 to 17.

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